1. Field of the Invention
The present invention relates to a technique for detecting variations in an image processing apparatus for dealing with line drawing map data or image data of an aerial photograph, a satellite photograph, or the like.
2. Description of the Related Art
Conventionally, some techniques relating to detection of variations in map and image data are known, for example, as disclosed in JP-A-11-328378, JP-A-5-181411, and so on.
According to the technique disclosed in JP-A-11-328378, a plan or three-dimensional digital map and a static image picked up from an area are used. The digital map is coordinate-converted into an image, and collated with the static image. Thus, heights of buildings, attribute information of ground objects, and so on, are detected so that the map is updated.
According to the technique disclosed in JP-A-5-181411, a central projection map is made up from a three-dimensional digital map, and collated with an aerial photograph image. Thus, variations over time or landscape information are extracted so that map information is updated automatically.
Each of the techniques disclosed in JP-A-11-328378 and JP-A-5-181411 is aimed at collating a line drawing map with an image to thereby update a detection result automatically. However, from a practical standpoint about a problem of accuracy in the detection result, there appear portions which can be updated automatically on the basis of a detection result and portions which cannot be updated automatically because of an ambiguous detection result. In the above-mentioned techniques, the latter portions are not taken into consideration so that there is a problem that a wrong detection result may be imported as it is.